The present invention relates to an electromagnetic actuating device according to the introductory clause of the main claim. The present invention further relates to a camshaft adjustment system having such an electromagnetic actuating device in connection with a camshaft adjustment device of an internal combustion engine as preferred use of the electromagnetic actuating device.
Generic electromagnetic actuating devices are generally known from the prior art; thus, for instance, the applicant's DE 201 14 466 U1 describes the structural composition of such an actuating device used for camshaft adjustment. Here, with the energizing of a stationary coil unit, an armature unit is driven which is movable relative thereto and to a stationary core unit. An elongated plunger unit, sitting against the armature unit and constructed on the end side for engaging into a camshaft adjustment groove of the adjustment device, is brought into an engagement position through the armature unit and brings about in this the desired camshaft adjustment. The adjustment groove, as actuating partner of the plunger means, then also provides for an (at least in sections) axial restoring of the plunger unit, namely in that an increased groove base induces a restoring movement.
In the practical realization of the described generic technology, alongside reliable, fail-safe suitability for large-scale production, the concern is primarily the dynamics and the actuating power of the armature- or respectively plunger movement. It is therefore important that the plunger of a relatively short time frame (predetermined by the actuation partner) can be brought from the initial position into the engagement position, which requires high magnetic forces (on the one hand on overcoming permanent-magnetic retention forces of the armature unit at the core region, on the other hand for achieving a high armature acceleration). In addition to this is the fact that in the technology which is used generically, the repulsive force (and therefore the acceleration force acting on the armature unit), the restoring force for returning the armature unit back must act over the entire effective operating stroke; long strokes, however, in particular in connection with high accelerated masses, then lead to a high mechanical load of the components, in turn with the requirement of correspondingly more robust design of the assemblies. The result is undesirably high (and costly) outlay in the actuating devices designed for large-scale production. Finally, in addition ageing- and temperature effects, in particular in the case of permanent magnet means which are usually provided on the armature side, are to be taken into consideration, which require additional design reserves in practical realization.
From the applicant's DE 10 2012 101 619 A1 an electromagnetic actuating device is known, which has detent means engaging radially-laterally onto the armature plunger. These detent means make it possible to increase the dynamics of the armature- and plunger movement, by the detent means only releasing after the exceeding of a predetermined actuating force and thus by the actuating movement taking place within a shortened actuating time. However, the disadvantage discussed above also exists here, that in principle the actuating force must be generated over the entire effective actuating stroke of the combined armature- and plunger unit, and also the restoring has to take place opposed to the entire stroke. Accordingly, in principle the same increased (and disadvantageous, for the reasons discussed above) dimensioning requirements exist as in the category-defining, generic prior art.